<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <title>圆形旋转loading</title>
        <style type="text/css">
            *{
                margin: 0;
                padding: 0;
            }
            .box{
                width: 50px;
                height:50px;
                margin: 100px;
                position: absolute;
            }
            .box:nth-of-type(2){
                transform: rotate(45deg);
            }
            .box p{
                width: 15px;
                height: 15px;
                background: #0000FF;
                border-radius: 50%;
                position: absolute;
                animation: run 1.5s infinite linear;
            }
            .box p:nth-of-type(1){ /*左上*/
                left: 0;
                top: 0;
            }
            .box p:nth-of-type(2){ /*右上*/
                right: 0;
                top: 0;
            }
            .box p:nth-of-type(3){ /*左下*/
                left: 0;
                bottom: 0;
            }
            .box p:nth-of-type(4){ /*右下*/
                right: 0;
                bottom: 0;
            }
            /*动画效果*/
            @keyframes run{
                0%{
                    transform: scale(0);
                }
                50%{
                    transform: scale(1);
                }
                100%{
                    transform: scale(0);
                }
            }
            /*延迟动画效果   负值是解决蹦动的效果*/
            .box:nth-of-type(1) p:nth-of-type(1){
                animation-delay: -0.1s;
            }
            .box:nth-of-type(2) p:nth-of-type(1){
                animation-delay: -0.3s;
            }
            .box:nth-of-type(1) p:nth-of-type(2){
                animation-delay: -0.5s;
            }
            .box:nth-of-type(2) p:nth-of-type(2){
                animation-delay: -0.7s;
            }
            .box:nth-of-type(1) p:nth-of-type(3){
                animation-delay: -0.9s;
            }
            .box:nth-of-type(2) p:nth-of-type(3){
                animation-delay: -1.1s;
            }
            .box:nth-of-type(1) p:nth-of-type(4){
                animation-delay: -1.3s;
            }
            .box:nth-of-type(2) p:nth-of-type(4){
                animation-delay: -1.5s;
            }
        </style>
    </head>
    <body>
        <div class="box">
            <p></p>
            <p></p>
            <p></p>
            <p></p>
        </div>
        <div class="box">
            <p></p>
            <p></p>
            <p></p>
            <p></p>
        </div>
    </body>
</html>